Automatic switch control system for classification yards



May 21, 1957 s. M. PHELPS AUTOMATIC SWITCH CONTROL SYSTEM FOR CLASSIFICATION YARDS Filed Nov. 12. 1953 4 Sheets-Sheet l v INVENTOR.

S. M. PHELPS HIS ATTORNEY May 21, 1957 Filed NOV. 12', 1953 s. M. PHELPS 2,793,287

AUTOMATIC SWITCH CONTROL SYSTEM FOR CLASSIFICATION YARDS 4 SheetE-Sheet 2 PIC-71.2 A. v A '--1 SM To OTHER I W F TRACK CIRCUITS -1 E L 8T I 34 8R 1 vs T A SOURCE (8)0 F ggNTAcTs 9D REGULAR 77 PO 0 LAY ARE SIMILARLY p A-C-SLPPLY X) T INCLUDED IN CIRCUITS B- FOR ALL l P g EBTNP OTHER TRACK SWITCHES 7 I I '3 b a l 39 4ol 4| v I J 42 L20 1 Q 1 I I 62 64 SgQ I I F i I66 'Tu l 098' p b g d l 8CCSI l d1 T|,-T--

- 88 SI A H STORAGE .1

b SACSIH I dz 1 I- LH I INVENTOR. -S.M. PHELPS Hl ATTORNEY y 21, 5 s. M. PHELPS 2,793,287

AUTOMATIC SWITCH CONTROL SYSTEM FOR CLASSIFICATION YARDS Filed NOV. 12., 1953 4 Sheets-Sheet 3 b4 Fl 6. 2 B.

8NWP BRWP IO-IZSDZ 3-5SD2 I I I I I 677? I I I I I I |I- -*-I- 52 I W I I "P IF I I I JI f I T 56 |I1 m I I I I 54 II'. sol

I58 I 'I I I I I -r I 73 I I I I ?2 L. I 23 70 25' 24 27 I INVENTOR.

Y -S.M. PHELPS HIS ATTORNEY May 21, 1957 Filed Ndv. 12, 1953 FIG. 2C.

5. M. PHELPS AUTOMATIC SWITCH CONTROL SYSTEM FOR CLASSIFICATION YARDS STORAGE A lO-IZSZ STORAGE lO-IZSI STORAGE 4 Sheets-Sheet 4 STORAGE STORAGE CONTROL OF SW. I2W.

CONTROL OF SW. IOW.

STORAGE FIG.

STORAGE CONTROL- OF SW. IIW.

AgK g TEA 0K W STORAGE CONTROL OF SW SW.

JFAPELQ TMEEES STORAGE CONTROL OF SW 7W was STORAGE GSI STORAGE CONTROL OF sw. 5w.

CONTROL OF SW.6W.

STORAGE STORAGE CONTROL -OF SW.4W.

STORAGE CONTROL OF SW. 2W.

TRACK-T INVENTOR.

S.M. PHELPS HIS ATTORNEY Unied S Pm1 f AUTOMATIC SWITCH'CONTROL SYSTEM FOR CLASSIFICATION YARDS Stuart Phelps, Rochester, N. Y., assiguor to General Railway Signal Company, Rochester, N. Y.

Application November 12, 1953, Serial No. 391,547

7 Claims. (Cl. 246-434) This invention relates to switch control systems for railway classification yards, and it more particularly pertains to switch control systems in which a route is automatically selected for each car, or cut of cars, subsequent to the manual designation of the track destination for that car or cut of cars.

Such a system is disclosed in the prior U. S. Patent No. 2,194,353, granted to N. C. L. Brown et al., March 19, 1940, and in the prior U. S. application of F. W. Brixner, et al., Ser. No. 179,462, filed August 15, 1950, now U. S. Patent 2,700,728 granted January 25, 1955. ofthis nature, route description storage relays are provided for the different track switches, and the route description that is designated for each car or cut of cars is transferred from one route storage to the next as the car progresses from track switch to track switch. This transfer is caused by the dropping away of the track relay for the detector track section of the associated track switch. The track circuits for these track relays are fed by alternating current supplied by the power utility company of the area, while the route description storage relays are operated by direct current from a battery. The alternating current track circuits, as compared to direct current track circuits, are desirable to provide higher shunting sensitivity.

Because of the possibility of power interruption of the alternating current source from time to time, a standby motor generator auxiliary alternating current supply is generally provided so that it is available upon failureof the normal source of alternating current. The time required for the auxiliary supply to take over is such as to permit the momentary dropping away of all track relays, with the resultant undesirable transfer of route descriptions.

The system according to the present invention provides that the. standby source of alternating current can be nor-j mally inactive andstarted only when needed. Thus, the standby motor generator can be started by the dropping away of a conventional poWer-ofi relay, for example. This is made possible by the provision. of a relay conveniently called a power detector relay, that is energized by the alternating current power that is feeding the track circuits, whether it be the normal alternating current source or the standby alternating current source. This relay is preferably made quicker to drop away and slower to pick up than the track relays.

Contacts of the power detector relay are used in the transfer circuits for the storage relays associated with the dilferent track switches to prevent transfer and cancellation of storages when the track relays are momentarily dropped away during the time interval required for the starting of the standby motor generator. When the track relays havehad time to be restored to their normally onergized positions by the standby energy, the power detector-relay is restored to its normally energized position,

and the route storage means is again subject to transfer and cancellation upon the dropping away of the track relays by the shunting of their respective track circuits.

In systems 2,793,287 Patented May 21, 19157 ice An object of the present invention, is to prevent transfer of route description storages when the track relays drop away because of an interruption of alternatnig current power feeding the track circuits.

Another object of the present invention is to prevent cancellation of route description storages when the track relays drop away because of an interruption of power feeding the track circuits.

Other objects, purposes, and characteristic features of the present invention will be in part obvious from the accompanying drawings and in part pointed out as the description of the invention progresses.

In describing the invention in detail, reference is made to the accompanying drawings in which similar reference characters are used to designate corresponding orassociated parts, and in which:

Fig. 1 is a diagram of the track layout of a typical c1assification yard for this embodiment of the present invention;

Figs. 2A, 2B and 20, when placed side by side, illustrate an automatic switching control system for the track layout illustrated in Fig. 1; and

Fig. 3 illustrates the manner in which the power detector relay prevents cancellation upon a power interruption of the alternating current power supply of the route description storage for the last track switch in a route.

The circuits illustrated are prepared more particularly to facilitate an understanding of the mode of operation of the system and the principles'involved, rather than to illustrate the specific construction and arrangement of parts that would be employed in practice. The symbols and have'been used to indicate the respective positive and negative connections to suitable batteries or other sources of direct current, and the symbols (BX) and (NX) have been used to indicate connections to the instantaneous positive and negative terminals of a source of alternating current such as might be provided by a power utility company.

With reference to Fig. 1, the hump yard layout for this embodiment of the present invention comprises 12 classification tracks that are connected through various track switches W to a single stretch of track extending over a hump. It is to be understood that the present invention is adaptable for practically any hump classifi-' switch 8W being in Group A, the'track switches SW and 12W being in group B, the switches SW and 10W being in group C, and the switches 2W, 4W, 6W, 7W, 9W and 1 1 W being in group D.

The track equipment is provided according to usual practice in classification yards of this character, the track switches W being operated by suitable power switch machines SM, and each of the track switches W having associated therewith a detector track section T that is fed by alternating current in a manner comparable to that illustrated in Fig. 2A for the feeding of the track circuit 8T associated with the track switch 8W.

In accordance with usual classification yard practice, a hump conductor station is provided near the hump, and located at that station is a suitable control panel such as the panel P illustrated in Fig. 2A. This panel has a push button PB for each of the classification tracks as a means by which the hump conductor can designate the destinations for the respective cars and cuts of cars.

' The route descriptions set up in response to the actuation of the push buttons PB can be provided in any suitable manner such as by the organization disclosed in the above mentioned prior Brown eta]. Patent No.'2,l94,353

a enas? or in the above mentioned prior application of F. W. Brix ner et al., Ser. No. 179,462 filed August 15, 1950, now U. S. Patent 2,700,728 granted January 25, 1955. For the purpose of simplification of the drawings for this .embodiment of the present invention, certain elements of'the system organization that havebeen taught by prior disclosures are illustratedin block form, some circuits being shown in detail in order to make clear how the-present invention is applied to these prior teachings .ofautornatic switching control systems,

With reference to Fig. 2A, a route description storage unit.8S3 is illustratedas being fed by route descriptions designated by operation of the push buttons P-B.:. on,the. hump con duetors panel P. This storage unit;is,. adapted= to tran sfer its storage over wires a, b', c, and d to .ajstorage unit 8S2 .when this un tais. available for, reception, of a ene a on.

estq a a elay .bank a d, a so ed. c ntrol apparatus that is more directly associated.vvith. the track switch W how in deta l h e ys ACsl. 3B.CS1., GC

and 8DCLS1 .constituting this; bank L of storage relays, and

relays aridifiSD l are associated, therewith-for .the

purpose of, governing. the delivery of route 7 description.

storages from the storage 8S2 to this bankofflstorage relays. Transfer audstorage control relays..3..5TN2 and 3+.5SD2; (see Fig.. 2B) are provided for governing .the.

transfer of the route storage of relays 8BCS1, SCCSI-and SDCSl to. a storage 'unit-3- 5S 2 (see. Fig. 2C) that .is as.- sociated ,with the track switches 3W and SW. Similarly, the relays 10- .1 2TN2 -and 10- 12SD2 are. provided .for. gov,

erningtransfer of. the routeldescription stored by relays.

purposes of governing cancellation of a route description.

stored by therelaysBACSl, 8BCS1, 8CCS1, and SDCSI. The, track; circuits arenormally fed from the power utility systemsourceof alternating current for the area, ancla standby alternating. current power supply is provid ed in the. ,formof. alternating current generator ACG- which is driven when standby power is needed by a motor- A- poweroff relay PO-is-provided for switching from the ,norrnalsource of... alternating current cnergy to the.

standby source and .vice-versa.

Attack; relay \T'Risprovid'ed foreach of the track cireultsand is operated througha suitable full-wave rectifier in a mannertypically illustrated for the operation of the track relay. BTRfromthe. track circuit 8T. V i

A, power 'detectorrelayLPD is provided for preventing transferand/or, cancellation of route descriptions during the changeover from one source of power to the other in a manner tobemoreflreadily apparent as the description progresses. Thisrelay is preferably made quicker to drop away and slower to. pick up than the track relays TR by the. inclusion in its control circuit of a suitable resistor R.

With reference to Fig. 3-, certain relays TR, CN, SD1 and PD are illustrated These relays areprovidedfforpurposes comparable -tolthos e described for relays bearing similar referencecharacters that are associatedwith the track switch- 8W. i

Contact have. been illustrated of suitable manual switch control levers. 8SML. and 2SML, and it is to be understood that these switchicontrol levers are of the. threeposi tioned type, a ndg in addition, the contacts illustratedare subject to being. opened by the pullingout of the.associ-. ated lever against the action .of.,a biasing spring, .these contacts being; used, forv the purposeof cancellation .in-a

mannerwhichhas beenpointed out .in they above..men-..

tioned. hrixner et all. application.

v g. o si er d. the. ener Or a iza io of ppa tus provided in the switch control system of one embodiment of the present invention, more specific consideration of the system will now be given with reference to the mode of operation upon consideration of typical operating conditions.

Operation Although reference is to be made 'to the abovementioned Brixner et al. application for a detail description of the automatic switching organization, a .brief.;con-.

relays (not shown) are provided in this storage unitfor these four characters comparable to therespective storage relays 8ACS1, SBCSI, 8CCS 1 and SDCSI which are provided for another storage unit. Each of these storage relays is selectively picked up or left in its dropped-awayposition in accordance with whether'a trackswitch'in the associated respective A, B, C, or D group is required to be in its normal or reverse positionfor the routethat has been designated.

Assuming that no prior route description is stored forthe track switch 8W, the route storage is immediately transferred over wires a, b, c, and d to a similar storage unit 882, and from the storage unit 882, the routedescription is transferred over-wires a1, b1, c1; and d1,- to the storage bank comprising the relays SACS-l; SBCSI',

SCCSL- and SDCSI. This transfer is'effectivein accordance-with-the picking up of transfer relays STNl and 8SD1 by the energization of circuits that have beendescribed for the energization ofsimilarly identified relays in the above mentioned Brixner et al. application. Relay 8SD1"(see Fig. 2A) is maintained'picked up by a stick circuit extending from (-1-), including front contacts 21 and 22 of relays 8TN1 and 8SD1 connected in multiple, wire 23, back contact 24 of relay 3-5TN2, back contact 25 of relay 10-12TN2, back contact 26; of relay 8DP,

wire 27, contact 28 of lever 8SML in its normal position,- back contact 29 of relay CN, back contact 30 of relay SCN I, and winding of relay 8SD1, to This stick circuit also includesback contact 3l of the track relay- 8T R c o nnected in multiple with back contact 26 of relay 8DP. Relay SAC Sl is eflective, with relay 8SD1 inits picked up position, to govern the operation, of the track switch 8W to itsj normal or reverse position in accordance with whether back contact 32 or front contact 32 of relay SAC SI is closed A With relay 88131; in its 1 picked up positidnfstick energy isapplied through, front contact 33 to. maintain the code'storage relays 8ACS1', SBCSI, SCCSI" and SDCSI in their seleeted positions according to .the route description code which is being stored.

The track relay 8TR' is associated with the detector tracksection 8T forthe track switch SW and isconnected to the track rails through a full, wave rectifier 34.. The track circuit is normally fed through front contacts.35 and 36 of the power oif relay PO from aconventional utility source of alternating current having its terminals designated as (BX) and (N X). All other track circuits are also ,fed through these contacts 35, and 36. of the power 'ofi relay PO.

Whenthe detector track section 3Tv becomes occupied by.a car for .whichthe route description-is, stored by the ars-sec a a r ost: a d. west; ns ewi routev description storage. is made toanother storageunit;

transfer will be made to the storage unit 3 -582 (see Fig. 20) in accordance with the energization of the transfer relays 3-5TN2 and 3-5SD2, the relay 3-5SD2 being energized by a circuit (not shown) similar to the circuit illustrated for relay 8SD1. The circuit by which the relay 3-5TN2 is energized at this time extends from including front contact 37 (see Fig. 2A) of relay PD, back contact 38 of relay STR, front contact 39 of relay 8SD1, back contact 40 of relay STNI, back contact 41 of relay STNP, front contact 42 of relay 8A CS1, wire 43, front contact 44 of relay 8NWP, back contact 45 of relay 3-5SD2, and winding of relay 3-5TN2, to The picking up of this relay closes a stick circuit for maintain-. ing relay 35TN 2 picked up extending from' including front contact 46 of relay 8SD1 (see Fig. 2A), wire 47, front contact 48 of relay 3-5TN2 and winding of relay 35TN2, to

The picking up of relay 3-5TN2 causes the picking up of the relay 3-5SD2 by the energization of a circuit (not shown) similar to the circuit shown for relaySSDl'and in a manner fully described in the above mentioned Brixner et a1. application. The wire d3'(see Fig. 2C) extending to the storage 3-5S2 is now selectively energized in accordance with the condition of relay -8DCS1 (see Fig.

2A), energy being applied to wire d3 when the relay relay 3-5TN2. Similarly, wire c3 is energized if relay 8CCS1 is picked up through front contact 53 of relay 3CCS1 (see Fig. 2A), wire 02, front contact 54 of relay 8NWP, front contact 55 of relay 3-5SD2, and front contact 56 of relay 3-5TN2. The wire b3 has energy applied thereto if relay 8BCS1 is picked up through front contact 57 of relay 8BCS1, wire b2, front contact 58 of relay 8NWP, front contact 59 of relay 35SD2, and front con tact 60 of relay 3-5T N2.

If the route is selected over the track switch 8W in a reverse position, instead of in a normal position as has been assumed, it will be readily understood that a similar mode of operation is effective involving the energization of relays 12T N2 and 10-12SD2, and the transfer of route description storage to the storage unit 10-1282 over wires [14, c4, and d4.

Relay SDP (see Fig. 2B) is picked up upon the entrance of a car into the track section 8T by the energizationof a circuit extending from including front contact 61 (see Fig. 2A) of relay 8SD1, back contact 62 of relay STNP, back contact 63 of relay 8TR, front contact 64 of relay PD, wire 65, and winding of relay 8DP, to This relay when picked up is maintained energized by a stick circuit directly dependent upon the relay 8SD1 extending from including front contact 61 (see Fig. 2A) of relay 8SD1, wire 66, front contact 67 of relay SDP, and winding of relay 8DP, to The picking up of relay SDP opens a branch of the stick circuit for relay SSDI at back contact 26 but the stick circuit for relay 8SD1 is maintained temporarily through back contact 31 of relay 8TR.

Relay 8D? becomes picked up at substantially the same time as the picking up of a transfer relay 3-5TN2 or 1tl-12TN2, and thus upon the opening of the stick circuit that has been described for relay 8SD1 by the picking up of a transfer relay TNZ, a new stick circuit becomes closed through the front contact 26 of relay SDP. Relay 8SD1 is slow enough in dropping away to bridge the cross over. time of the contact 26 in shifting to select the new stick circuit. Thus, a relay 8SD1 is maintained picked up by a new stick circuit (assuming relay 3-5TN2 to be energized), extending from including front contact 68 of relay 8SD1, wire 69, front contact 70 of relay 8NWP,- front contact 71 of relay 3-5TN2, back contact 72 of contact 28 of lever 8SML, back contact 29 of relay CN,

back contact 30 of relay CNl, and winding of relay When'the relay .35SD2 (assuming a'route over track switch 8W in its normal position) becomes picked up, relay-8SD1 is deenergized by the opening of its stick circuit at back contact 72 (see Fig. 2B), but because of the slow drop away characteristics of relay SSDl, this relay is maintained picked up long enough for the energization of the transfer circuits that have been described for transfer of the route description to the storage 3-582. At the end of this time interval, the relay 8SD1 is dropped away and the dropping away of this relay cancels the storage of the route description by the relays-SACSI,

8BCS1, 8CCS1 and 8DCS1 by the opening of the stick circuits for these relays at front contact 33. I

Having thus described the normal mode of operation for the automatic transfer of route descriptions as selected by the position of the track switch SW and as rendered effective by the presence of the car in the detector track section 8T, it should be readily apparent that a similar mode of operation is effective for each of the other track switches to be encountered by the passage of a car from the hump to a predetermined classification track, this apparatus being indicated in block form according to the block diagram of Fig. 2C.

From the mode of operation of the system as it has been described, it will be apparent that the transfer of a route description is rendered effective by the picking up of a transfer relay TN upon the dropping away of a track relay TR for an associated detector track section. Thus, as has been described, a relay 35TN2 or 10-12TN2 is picked up in response to the dropping away of the track relay 8TR which is controlled by the track circuit for the track section 8T.

The cancellation of a route description as stored by the relays SACSl, 8BCS1, SCCSI and 8DCS1 in combination with relay 8SD1 has been described as having been rendered effective when the track relay 8TR for the associated track section 8T is dropped away after transfer of a route description has been effected. Involved in this cancellation is the picking up of relay 8DP for the apparatus associated with the track switch 8W, this relay being picked up by the closure of back contact 63 of the track relay STR. Relay SDP when picked up selects a stick circuit for the storage relay 8SD1 dependent upon the front contact of a transfer relay TN and the back contact of a relay SD. If the relay 8D? were to be permitted to be picked up, at a time when no transfer relay 3-5TN2 or 10-12TN2 is picked up, it will be obvious that the relay 8SD1 would be dropped away, and thus the route description stored by the relays 8ACS1, 8BCS1, 8CCS1 and 8DCS1 would be cancelled.

From the foregoing description, it will be apparent that should the track relay 8TR, for example, be momentarily dropped away by a momentary power interruption of the power feeding its track circuit, were it not for the present invention, a route description stored by the relays 3ACS1, SBCSl, 8CCS1 and SDCSI, combined with relay SSDl would be transferred the same as if the track section 8T had become occupied by a car as has been described. This Would, of course, be an improper mode of operation which might get the route description storages out of step with the cars for which they are provided. Thus, to maintain proper operation under conditions of masses momentary power interruption, the power"- detecton relay PD is provided in a mannertorenderthe dropping away ofany track relay ineffective to cause transfer orcancellation of a route description 'underconditions. where that track relays TR are deener-gized by reason ofpowerinterruption-ratherthan by reason of their respective track circuits being shunted by=-thepassage of cars.

Thesystem isthus inoperative for the transfer of route descriptions while the power detector relay PD is in its dropped away position, but-this-relay is-in its dropped" the.;auxiliary pozvver= supply:- is-being-started. In other words; if a car: enters a detector.trackcircuit while: the

detectorrelay PD: is dropped-:away, the track relay. TR

forthe associated track circuit will :remain dropped: away. when the: detector relay PDis'pickecl up, and .at,;thi's.time

transfenof the-route descriptionfor the carshunting vthe associatedtrack circuitwill :be, rendered effective by the normal mode ofoperation. Thismodenof. operation is also true for a car-entering-a, track circuitsubstantially.

simultaneously with. the, failure of the normal power; supp y.

The power detector relay PD (see Fig. 2A), which is provided, to: prevent theabove described undesirable operation; upon ,an interruption of-powenis energized Whem.

ever-energy-from either. a normal or. a standby source of alternating current is applied tothe track circuits; Thus,

if the track circuits areenergized from-thenormal source. of alternating; current, the power; detector relayyPD is energized through front contacts 35; and 36 of, relay PO, resistor R, and, full wave-rectifier 76. Ifthe track circuits are energized-.fromthe standby source, they are energized through the back contacts 35 and 36:-of the power offrelay PO and thus the-power detector relay PDis also energized from the standby 1 source generator -ACG .when

the poweroff relay PO is inv its dropped away position. Relay P is ,inits dropped away position whenever there is an, interruption of the normal source of alternating current because this relay is connected directly to the normal source through the full. wave rectifier 77.

With thepowerroii relay PO'in itsdropped away position, ;direct current. energy isapplied through back contact 78. of relay-PO to the motor M which drivesthe alternating current generator ACG. This generator-is connected through back-contacts and 36 of relay. PO

to. the respective track circuits, and also to the power detector relay PD to cause thisrelay to be picked up.

From the circuit organization that has been described, it will be apparent that upon an interruption of the normal source of power, the power offrelay becomes dropped away. The dropping away of this relay causes the initiation of the standby motor generator and connects the output of the generator to feed the track circuits. In the time required for initiation of the motor generator, however, thepowcr detector. relay PD and the track relays become momentarily dropped away.

Because of the resistor R being connected in-the circuit for the windingpf the power detector relay PD, this relay is made quicker to drop away and slower to pick up than the. track relays. Thus, a contact of relay PD in series with a contact of a track relay TR in a circuit can render the operation. of the track relay TR effective to control the circuit except when the power-detector rclay PD is actuated. to its dropped away position.-

More specifically, for exampleupon the dropping away track. relay @8'1E'R2 becomes,- closed, neither; :of zthese trans;- 1 fer relays can :bepickedvup, as; is the. case,.accord1ng to the .normal". operation upon the. dropping. away, of the' track relaySTR'. Thus, there-can .be notransferof route description eifected when-the track relay -8TR-is droppedaway under: these: conditions.

If the.relay.8DP were to bepermittedto beipicked up under:.the -,.abo,ve described conditionsof power interruptioninaccordancewviththe closing of back contact 63 Of'Il'flCk: relay STR, the; shifting ,of itscontact 26"would open the stick circuit for; the relay 88131 inthatthere could be no rstick circuit closed. as is providedin normal operation through-a front-contact. of a transfer relay 3-5TN2=.or 10-'12TN2.' It is, therefore, provided thattion, the front-contact. 64 of' relayPDwill openthecirouit forrelay SDBbefore-the circuit for this-.relaycan .be closed by the. closure of back contact 63 of the track.

relay. 8TR.

It is;tov be-understood1thatthe circuitassociated with the other trackswitches are organized according to the.

principles; thathaive been described -with respect tothe control ofthe relays 1012TN2,35'I N2 and SDP. This is true for each of the other track switches to be encountered in a route except the .last track switch where no transfer'is made and only a cancellation of the route description need-be considered.

'Dhe route-description for' each of these last trackswitches is normallycancelled upon-entrance of *a-car into thedetector track, section for. the associated track switch by the .opening'of a stick circuit shown,'for ex-.

ample,- in Fig. 3 fonthestorage control. relay 2SD1 which:

is,associat.ed-with1the track. switch 2W. This-relay is held up when thereisanassociated storage through front contact; 79 ofrelay 2SD1 connected inmultiple with frontv contact 80 of relay 2TN1, front contact 81 of relay 2TR connected in multiple with front contact 82- of relay ZDP, contact 83 voi -relay ZSML, and .backcontact84 of. relay CN. To prevent the dropping away of. relay 2SD1 in case front contact 81.of the track relay 2TR is momentarily opened, an auxiliary stick circuit is provided for the relay. 2SD1 extending from including back contact -85 of relay PD, front contact 86 of relay 2SD1, and winding of relay 2SD1, to This circuit. organization provides that in case the track relay ZTR is dropped away, because of a momentary power interruption ofits track/feed, the relay PD becomes dropped away first to close the. auxiliary stick circuit so as to maintain the relay 2SD1 energized until the track .relay ZTR has.

. relays SDI for theother trackswitohes that. are thelast to be.v operatedina route from the hump-to the different classification tracks.

Having thus described an automatic switching system fora classification yard asoneembodiment of the present invention, it is to be understood that the description as set forth has been primarily for the purpose of illustrating the principles and mode of operation rather than for limiting the: number of forms the present invention may assume, audit is to be further-understood that various modifications, adaptations and alterations may be made with respect. to the specific form shown in accordance. with. the requirements of'practicewithin. the scope of the appending claims.

What 'I' claim is:

1..A railway switch control system1of the character described for-positioning: a ,groupof track switches in succession-in: a classification.yardhaving. detector track sections for-the respective track switchescomprising a uormall-ys'active soureeref-energy, a ,nonnallyinactive source of energy, a power-off relay energized only from said normally active source of energy, said power-E relay when deenergized being effective to render said normally inactive source active, a track circuit for each of the detector track sections having a track relay, said track circuit being energized from said normally active source of energy when said power-off relay is picked up and from said normally inactive source of energy when said powerotf relay is dropped away, a power detector relay, means for energizing said power detector relay by whichever of said sources of energy that is energizing said track circuits, an independent source of energy, route description storage means for each of the track switches energized by said independent source of energy and subject to cancellation by the deenergization of the track relay for the track section of the associated track switch, and means for rendering the cancellation of said route storage means by the dropping away of the associated track relay ineffective when said power detector relay is in its deenergized position.

2. In a railway switch control system for positioning a group of track switches in succession in a classification yard having detector track sections for the respective track switches, a normally active source of alternating current,

a normally inactive source of alternating current, a poweroif relay energized only from said normally active source of alternating current, said power-off relay when deenere gized being effective to render said normally inactive source active, a track circuit for each of the detector track sections having a track relay, said track circuit being energized from said normally active source of alternating current when said power-0E relay is picked up and from said normally inactive source when said power-off relay is dropped away, a power detector relay energized by whichever of said sources of alternating current is effective for energizing said track circuits, said power detector relay being quicker to drop away when deenergized than said track relays, a source of direct current, route description storage relays for each of the track switches energized by said source of direct current and subject to cancellation by the deenergization of the track relay for the detector track section of the associated track switch, and means for rendering the cancellation of said route storage means by the dropping away of the associated track relay ineffective when said power detector relay is in its deenergized position.

3. In a railway switch control system for positioning a group of track switches in a classificationyard having detector track sections for the respective track switches, a source of alternating current, a track circuit for each of the detector track sections having a track relay, said track circuit being normally energized from said source of alternating current, a power detector relay normally energized from said source of alternating current, a source of direct current, route description storage means for each of the track switches energized by said source of direct current and subject to cancellation by the deenergization of the track relay for the detector track section of the associated track switch, and means for rendering the cancellation of said route storage means by the dropping away of the track relay for the associated track switch inefiective provided that said power detector relay is dropped away.

4. A railway switch control system of the character described, for positioning a succession of track switches in a classification yard having detector track sections for the respective track switches comprising, a normally active source of energy, a normally inactive source of energy, a track circuit for each of the detector track sections having a track relay, said track circuit being energized selectively from said norm-ally active source of energy or from said normally inactive source of energy, a power detector relay, circuit means for energizing said power detector relay from whichever of said energy sources is feeding said track circuit, an independent sourceor energy, route, description storage means for each of the track switches selectively energized from said independent source of energy to store a route description and subject to cancellation of a route description in response to the deenergization of the track relay for the detector track section of the associated track switch, and means for rendering the cancellation of a route description stored by said route description storage means in response to the deenergization of the track relay for the detector track section of the associated track switch ineffective when said power detector relay is in its deenergized position.

5. In a railway switch control system for positioning a succession of track switches in a classification yard having detector track sections for the respective track switches, a first source of alternating current, a second source of alternating current, a track circuit for each of the detector track sections having a track relay, said track circuit being energized selectively from said first source of alternating current or from said second source of alternating current, a power detector relay, circuit means for energizing said power detector relay from the same source of energy at all times that feeds said track circuits, route description storage means for each of the track switches effective when energized to store a route description, and transfer means for certain of the track switches for effecting the transfer of the route description stored by the associated route description storage means to the route description storage means for the next track switch in the route of a car when said track relay for the track circuit of the associated track switch is dropped away, said transfer means being ineffective upon the dropping away of the track relay for the associated track switch if said power detector relay is in its dropped away position.

6. In a railway switch control system of the character described for positioning track switches successively as a car progresses in a classification yard, a detector track section for each of the track switchs, a source of alternat ing current, a track circuit for each of the detector track sections having a track relay and energized from said source of alternating current, a power detector relay, circuit means for energizing said power detector relay from the same source of energy that feeds said track circuits, route description storage means for each of the track switches effective when energized to store a route description, and transfer means for each of the track I switches for effecting transfer of the route description stored by the associated route description storage means for the next track switch in the route of a car when said track relay for the track circuit of the associated track switch is dropped away, said transfer means being ineffective upon the dropping away of said track relay for the associated track switch if said power detector relay is in its dropped away position.

7. A railway switch control system of the character described for positioning a group of track switches successively in a classification yard having detector track sections for the respective track switches comprising, a first source of alternating current, a second source of alternating current, a power off relay energized only from said first source of alternating current, a track circuit for each of the detector track sections having a track relay, circuit means for energizing said track relay from said first source of alternating current when said power-ofif relay is picked up and from said second source of alternating current when said power-01f relay is dropped away, a power detector relay, circuit means for energizing said power detector relay at all times from the same source of energy that feeds said track circuits, route description storage means for each of the track switches effective when energized to store a route description, and transfer means for certain of the track switches for effecting transfer of the route description stored by the associated route descrip- 1 1 12 tionzstorag means ,tothQ-I'O Q d s riptionestoragem ans.e References :citedii the. file .of this patent: fonthe lext detector track switech in t he route 0f v a car UNITED STATES vPZAHENI-S when sald ,track relay for the track clrcmt of the 3850.: v ciatedtrackvswitch is dropped away; said transfer means Spray 1931 being inefiective upon the dropping away of the track re- 5 2,167,027 Lay July 25, 1939 1ay, for the associated track switch if said power detector 2194353 a1 19, 1940 2,268,193 Fallor' Dec. 30; 1941 relay is in its; droppedraway. position; 

